The present invention relates to a method that allows several providers of mobile radio services to jointly use a radio access network of a mobile radio system. Several reasons (for example financial or regulatory) nowadays force mobile radio providers to efficiently utilize, jointly operate or share parts of the infrastructure for providing mobile radio services.
The present state-of-the-art is reflected in national roaming agreements, where the mobile radio subscribers of one mobile radio operator are permitted to use the mobile access network and also the core network of the respective roaming partner. The methods for providing these roaming services are mainly based on standardized methods, for example of the 3GPP standard [www.3gpp.org]. In addition, the currently employed linkage between radio access network and the core network of a mobile radio provider makes it impossible to select another core network, for example a Mobile Switching Center (MSC) for providing circuit-switched (CS) connections, for example for voice connections, or another Serving GPRS Node (SGSN) for providing packet-switched (PS) connections, for example Internet access. The basic architecture of a conventional mobile radio network is shown in FIG. 1. The radio access networks (RAN) 4, 5 and the respective core networks (CN) 1, 2 of the mobile radio operator A and B are implemented in both (or several) mobile radio operators in parallel. If roaming agreements between the mobile radio operators exist, the mobile radio subscribers of operator A can, for example, use in areas without mobile radio service by operator A the mobile radio services of operator B via its radio access and core network 4, 2. However, in this case, the operator B provides all the services for the mobile radio subscriber of A. This situation has, inter alia, the disadvantage that the operators A and B must reconcile the rendered mobile radio services; however, operator B may not be able to offer all the services offered by operator A. Frequently, national roaming agreements, in which mobile radio operators lacking an equal market position may enter, may therefore be one-sided.